CODEWITHSUNDEEP
javascriptphphash
nabizan
nabizan

Reputation: 3365

Computing hash in PHP yields different results on local and test environments.

I'm trying to server-side validate a hash generated on the client side.

My client-side js code looks like this:

_hash: function(value) {
    var hash = 5381;
    for (var i = 0; i < value.length; i++) {
        hash = ((hash << 5) + hash) + value.charCodeAt(i);
    }
    return hash;
}

and my server-side php code like this:

$hash = 5381;
$value = strtoupper($input);
for($i = 0; $i < strlen($value); $i++) {
    $hash = (($hash << 5) + $hash) + ord(substr($value, $i));
}

When applied to the string "FMQXXU", you should get -1329107890 on either side.

Both scripts work perfectly on my local environment, but when i move to test on a different machine, only the js code works. The php code returns 6952222944334.

The local php is version 5.3.8, the test php is version 5.3.3.

Why do I get different results?

Upvotes: 2

Views: 100

Answers (1)

T. Coeugnet
T. Coeugnet

Reputation: 145

You can use this function to convert 64 bits to 32 bits :

function to_32bits($val) {
    $sign = 1 << 31;
    return $val & ($sign) ? -(~($val & 0x7fffffff) + 1 + ($sign)) : $val & 0xffffffff;
}

Example : 

$a = -1329107890;
$b = 6952222944334;

function to_32bits($val) {
    $sign = 1 << 31;
    return $val & $sign ? -(~($val & 0x7fffffff) + 1 + $sign) : $val & 0xffffffff;
}

echo $a . ' ' . to_32bits($b);

Will output : -1329107890 -1329107890

I'm not sure if there is a better way to do the conversion.

Upvotes: 1

Related Questions